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SubjectRe: [PATCH 1/5] cpumask: update irq_desc to use cpumask_var_t: fix
Yinghai Lu wrote:
...
> static void init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
> struct irq_desc *desc, int cpu)
> {
> memcpy(desc, old_desc, sizeof(struct irq_desc));
>
>
> will overwrite new_desc->affinity and pending_mask
>
> YH

I've appended this to the patchset:

Subject: cpumask: fix bug in use cpumask_var_t in irq_desc

Impact: fix bug where new irq_desc uses old cpumask pointers which are freed.

As Yinghai pointed out, init_copy_one_irq_desc() copies the old desc to
the new desc overwriting the cpumask pointers. Since the old_desc and
the cpumask pointers are freed, then memory corruption will occur if
these old pointers are used.

Move the allocation of these pointers to after the copy.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yinghai@kernel.org>
---
include/linux/irq.h | 9 +++++++--
kernel/irq/handle.c | 8 +-------
kernel/irq/numa_migrate.c | 13 ++++++++-----
3 files changed, 16 insertions(+), 14 deletions(-)
--- linux-2.6-for-ingo.orig/include/linux/irq.h
+++ linux-2.6-for-ingo/include/linux/irq.h
@@ -426,15 +426,18 @@ extern int set_irq_msi(unsigned int irq,
/**
* init_alloc_desc_masks - allocate cpumasks for irq_desc
* @desc: pointer to irq_desc struct
+ * @cpu: cpu which will be handling the cpumasks
* @boot: true if need bootmem
*
* Allocates affinity and pending_mask cpumask if required.
* Returns true if successful (or not required).
* Side effect: affinity has all bits set, pending_mask has all bits clear.
*/
-static inline bool init_alloc_desc_masks(struct irq_desc *desc, int node,
+static inline bool init_alloc_desc_masks(struct irq_desc *desc, int cpu,
bool boot)
{
+ int node;
+
if (boot) {
alloc_bootmem_cpumask_var(&desc->affinity);
cpumask_setall(desc->affinity);
@@ -446,6 +449,8 @@ static inline bool init_alloc_desc_masks
return true;
}

+ node = cpu_to_node(cpu);
+
if (!alloc_cpumask_var_node(&desc->affinity, GFP_ATOMIC, node))
return false;
cpumask_setall(desc->affinity);
@@ -484,7 +489,7 @@ static inline void init_copy_desc_masks(

#else /* !CONFIG_SMP */

-static inline bool init_alloc_desc_masks(struct irq_desc *desc, int node,
+static inline bool init_alloc_desc_masks(struct irq_desc *desc, int cpu,
bool boot)
{
return true;
--- linux-2.6-for-ingo.orig/kernel/irq/handle.c
+++ linux-2.6-for-ingo/kernel/irq/handle.c
@@ -85,8 +85,6 @@ void init_kstat_irqs(struct irq_desc *de

static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
{
- int node = cpu_to_node(cpu);
-
memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));

spin_lock_init(&desc->lock);
@@ -100,7 +98,7 @@ static void init_one_irq_desc(int irq, s
printk(KERN_ERR "can not alloc kstat_irqs\n");
BUG_ON(1);
}
- if (!init_alloc_desc_masks(desc, node, false)) {
+ if (!init_alloc_desc_masks(desc, cpu, false)) {
printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
BUG_ON(1);
}
@@ -188,10 +186,6 @@ struct irq_desc *irq_to_desc_alloc_cpu(u
printk(KERN_ERR "can not alloc irq_desc\n");
BUG_ON(1);
}
- if (!init_alloc_desc_masks(desc, node, false)) {
- printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
- BUG_ON(1);
- }
init_one_irq_desc(irq, desc, cpu);

irq_desc_ptrs[irq] = desc;
--- linux-2.6-for-ingo.orig/kernel/irq/numa_migrate.c
+++ linux-2.6-for-ingo/kernel/irq/numa_migrate.c
@@ -38,16 +38,22 @@ static void free_kstat_irqs(struct irq_d
old_desc->kstat_irqs = NULL;
}

-static void init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
+static bool init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
struct irq_desc *desc, int cpu)
{
memcpy(desc, old_desc, sizeof(struct irq_desc));
+ if (!init_alloc_desc_masks(desc, cpu, false)) {
+ printk(KERN_ERR "irq %d: can not get new irq_desc cpumask "
+ "for migration.\n", irq);
+ return false;
+ }
spin_lock_init(&desc->lock);
desc->cpu = cpu;
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
init_copy_kstat_irqs(old_desc, desc, cpu, nr_cpu_ids);
init_copy_desc_masks(old_desc, desc);
arch_init_copy_chip_data(old_desc, desc, cpu);
+ return true;
}

static void free_one_irq_desc(struct irq_desc *old_desc, struct irq_desc *desc)
@@ -83,15 +89,12 @@ static struct irq_desc *__real_move_irq_
desc = old_desc;
goto out_unlock;
}
- if (!init_alloc_desc_masks(desc, node, false)) {
- printk(KERN_ERR "irq %d: can not get new irq_desc cpumask "
- "for migration.\n", irq);
+ if (!init_copy_one_irq_desc(irq, old_desc, desc, cpu)) {
/* still use old one */
kfree(desc);
desc = old_desc;
goto out_unlock;
}
- init_copy_one_irq_desc(irq, old_desc, desc, cpu);

irq_desc_ptrs[irq] = desc;



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